There were lots of questions about my 60 percent number after Donald Trump seemed to come to an agreement with House Speaker Paul Ryan (R-WI) and Senate Majority Leader Mitch McConnell (R-KY) last week over funding for the wall he wants to build between the U.S. and Mexico.

But Trump has again proved that he can’t be taken at his word about a shutdown. He tweeted this out a little after 9 am EDT this morning.

I would be willing to “shut down” government if the Democrats do not give us the votes for Border Security, which includes the Wall! Must get rid of Lottery, Catch & Release etc. and finally go to system of Immigration based on MERIT! We need great people coming into our Country!

Today’s tweet provides some important clues as to the possibility of a shutdown.

First, Trump is using the threat of a shutdown to raise the immigration issue with his base. As I’ve said before, that may be very critical for Trump this fall.

Second, he’s signalling that he’ll blame House and Senate Democrats and, therefore, telling the congressional GOP leadership that the shutdown they’re desperate to avoid is less important to him than the wall.

Third, Trump is also telling Ryan and McConnell that he hasn’t yet agreed to anything.

As a result…I’m maintaining my previous estimate that there’s a 60 percent chance of a federal government shutdown this fall. I’m expecting that to go higher in the days ahead.